What is the Korean monsoon season (장마) like, and how should foreigners prepare for weeks of heavy rain?

Korea's jangma (장마) monsoon season runs from late June through late July, dumping about 30 to 40 percent of the country's annual rainfall in just 3 to 4 weeks. Heavy downpours can be intense (50mm+ per hour during peak storms), and the air is hot and oppressively humid (80 to 95 percent), making it feel sticky even indoors without AC. Localized flash flooding in low-lying areas like Gangnam Station underground passages happens almost every year.

To prepare, get a sturdy umbrella with a wide canopy (avoid the 5,000 won convenience store ones, which break in wind), waterproof shoes or rain boots, and a light raincoat. Quick-dry synthetic clothing beats cotton, which stays soggy. Dehumidifiers (제습기) and silica gel packs are essential for closets and shoes to prevent mold. Run your AC's dehumidify mode (제습 모드) instead of cooling for energy savings. For flooding safety, never enter underground passages or basements during heavy rain warnings, avoid driving through flooded streets, and download the Emergency Ready App for real-time alerts. The Korea Meteorological Administration (kma.go.kr/eng) issues 3-day rain forecasts and storm warnings (호우경보, 호우주의보) you should monitor. Flood insurance is included in basic homeowner policies. For mental health, the gray skies for weeks can cause low mood, so plan indoor activities, stock up on Vitamin D, and use bright lighting at home.